The Composite Blues scale is a versatile scale used in many genres of music.
It is a nine-note scale which, in the key of C, contains the following notes
The composite blues scale’s construction can be viewed from several perspectives:
as a combination of the Mixolydian mode and the blues scale with the same root notes (it is also sometimes called the Mixolydian/blues hybrid scale)
as a combination of two blues scales whose root notes are a minor third apart
or, as a combination of the blues scale and major pentatonic scales with the same root notes.
The composite blues scale is typically used over dominant seventh chords and Mixolydian progressions. It is ideal for this use as it contains the flat seventh and altered extensions (sharp ninth and flat five) which are often used over dominant harmony
The inclusion of both the major and minor thirds and the flat fifth (blue note) lends itself to use in blues settings,
while the series of semitones found between scale degrees 2 and 5 lends itself to use in Mixolydian and chromatic settings. It is these features which allows the composite scale to be used in a variety of genres.
In a traditional twelve-bar blues setting, the blues scale which shares the same root note as the key of the tune can be used to solo over the complete twelve bar progression. Alternatively, the blues scale may be coloured using notes taken from the composite blues scale. For example, in the tune Boom Boom, by John Lee Hooker, Hooker essentially creates all of the fills and solos using notes derived from the F Blues scale –
this excerpt shows part of the intro riff
However, at several instances over chord IV (B flat seventh) Hooker includes notes derived from the B flat blues scale
(this example occurs at 1:08 of the tune)
and the composite blues scale (this occurs at 1:43)
Of course, in this instance, Hooker could simply be thinking in terms of the B flat seventh’s chord notes. Using the chord-note approach Hooker could also play the dyad (D-A flat): these notes being the third and seventh of the B flat seventh chord.
At 1:50, this time over chord V, Hooker uses an A note to approach the A flat note of chord IV in the following bar.
The inclusion of the A note with the F blues scale brings the note-group closer to the F composite blues scale. Here, the addition of the A and D notes to the familiar F blues scale gives eight of the nine notes in the F composite blues scale.
As noted earlier, the composite blues scale can be used over dominant harmony, such as found in a traditional major, or ‘dominant’ blues, or Mixolydian progressions.
The opening progression from the tune Paradise City, by Guns N’ Roses is in G MIxolydian (Note: the guitars are tuned down a semitone sounding in G flat, however, in this article, for ease of discussion all guitars will be notated at standard pitch).
While the lead guitarist, Slash, essentially uses notes from the G major pentatonic to play the riff over the Mixolydian progression (beginning at 1:00), he does include a C note on the second repeat (1:17).
This C note is found in the G Mixolydian mode and the G composite blues scale. Of course, as with the John Lee Hooker example discussed previously, Slash could simply be thinking in terms of chord notes: the C note is played over the C chord. However, throughout the song the G composite blues scale is used, not only as a choice for solos but also as a compositional tool.
Looking first at the scale as a compositional tool: after the opening Mixolydian progression the verse progression (G5 – B flat – G5 – C – B flat – G5 – B flat – G5 – B flat – C – G5, beginning at 1:30) uses chords derived from the G composite blues scale
The ‘5’ chords of the chord progression which immediately precedes the first verse (G5 – B flat 5 – G5 – C5 – B flat 5 – G5 – B flat 5 – G5 – F5 – C5 – B flat 5, beginning at 1:20) can all be found in the G blues scale.
However, the full triads found in the verse progression can only be derived from the G composite blues scale (the only exception is the B flat major triad which can also be found in the G blues scale). During the first guitar solo the chords used at 3:16 (A5 – C5 – A5 – D5 – C5) are also only found in the G composite blues scale.
Slash’s note choices over this solo are essentially derived from the G blues scale and the A blues scale over the A5 – C5 progression discussed above. Exceptions to this include the use of the G composite blues scale, or the E blues scale, for the semitone move, B flat to B natural, at 3:14
and at 3:27, over the C – D5 – C5 – D5 progression, Slash uses the C composite blues scale to derive his note choices.
During the ‘double time’ section beginning at 4:47, Slash’s note choices are again essentially taken from the G and E blues scales although, beginning at 5:58 he uses the complete G composite blues scale
Using the Composite Blues Scale to Unify Related Keys